The bioprocessing industry has traditionally used stainless steel systems and piping in manufacturing processes for fermentation and cell culture. These devices are designed to be steam sterilized and reused. Cleaning and sterilization are however costly labor-intensive operations. Moreover, the installed cost of these traditional systems with the requisite piping and utilities is often prohibitive. Furthermore, these systems are typically designed for a specific process, and cannot be easily reconfigured for new applications. These limitations have led to adoption of a new approach over the last ten years—that of using plastic, single-use disposable bags and tubing, to replace the usual stainless steel tanks.
In particular bioreactors, traditionally made of stainless steel, have been replaced in many applications by disposable bags which are rocked or stirred to provide the necessary aeration and mixing necessary for cell culture. These single-use bags are typically sterile and eliminate the costly and time-consuming steps of cleaning and sterilization. The bags are designed to maintain a sterile environment during operation thereby minimizing the risk of contamination.
Bags containing sterile fluids are used in the bioprocessing industry for formulation, storage, transfer, processing, and transportation. Sterile conditions must be maintained during these operations, and the bags are usually sealed to prevent contamination. Commonly used bags are of the “pillow style,” mainly because these can be manufactured at low cost by seaming together two flexible sheets of plastic. Thus, the most conventional bags are two-dimensional.
In many applications, the components contained in a bag must be mixed before use. For example, a product may be formulated from the blending of a dry powder into a fluid. In other situations, the product contained in a bag may separate during transport or storage, and require mixing before use. The mixing situation puts extra demands on the bag in relation to strength.
In the corners of conventional three-dimensional plastic bags, three films meet and are joined together, usually by heat-sealing. Every corner of a three dimensional bag has a risk of leak due to two reasons: improper seal process and fatigue of the heat-sealed area. The root cause is lack of material at the spot where three films are sealed together.
Therefore, there is a need for an improved three-dimensional plastic bag which resists fatigue (and leakage) during handling and packaging and is easy to produce.